In manufacture of an SOI wafer by the ion implantation delamination method, when a bond wafer for forming an SOI layer (Silicon On Insulator layer, or Semiconductor On Insulator in a broad sense) and a base wafer are bonded through an oxide film, and then subjected to a heat treatment (a delamination heat treatment) to perform a delamination at an ion-implanted layer, the wafers just after delamination are taken out from a heat treatment furnace with which the delamination heat treatment has been performed in a state that an SOI layer surface (a delaminating plane) of the SOI wafer faces to a surface (a delaminating plane) of the bond wafer (See Patent Document 1, etc.).
When a bond wafer on which an oxide film has been formed and a base wafer are bonded to manufacture an SOI wafer, the SOI wafer warps in a convex shape on the delaminating plane side due to a buried oxide film which has been transferred from a surface of the bond wafer by the delamination heat treatment, whereas the bond wafer after delamination warps in a concave shape on the delaminating plane side in contrast to the SOI wafer because the front surface oxide film is separated and the oxide film remains only on the back surface. Although a magnitude of the warpage is determined depending on a thickness of the transferred oxide film, a contact between the SOI wafer and the bond wafer after delamination hardly occurs because magnitudes of the warpages of these wafers are almost the same.
In practice, however, there is also the influence of a warp shape formed during wafer processing. Therefore, for example, if the bond wafer warps convexly during wafer processing, the bond wafer after delamination is formed into a shape obtained by subtracting the convex shape formed during the wafer processing from the concave shape due to the influence of the back surface oxide film.
In this case, a mismatch in warp shape between the SOI wafer and the bond wafer after delamination is caused. More specifically, a magnitude of the concave warp of the bond wafer after delamination becomes small compared with a magnitude of the convex warp of the SOI wafer.
In addition, in the ion implantation delamination method by the so-called coimplantation in which the ion implantation is performed by implanting two types of ion, for example, a hydrogen ion and a helium ion to form an ion-implanted layer at which delamination is caused, if the helium ion is implanted more deeply than the hydrogen ion, a helium ion-implanted layer remains in the bond wafer still after delamination while a hydrogen ion-implanted layer is divided into an SOI side and the bond wafer after delamination because the delamination is caused at the hydrogen ion-implanted layer. In this case, warping force by which the bond wafer after delamination is warped so as to have a convex shape operates on the bond wafer after delamination by existence of the helium ion-implanted layer, thereby causing the mismatch in warp shape with the SOI wafer.